The overall aim of the third year of the national evaluation of TPPs, spanning October 1997 to September 1998, was to identify the ingredients of successful devolved purchasing based in primary care by in-depth study of twelve first wave TPPs. The analysis presented here considers eleven of the case studies and links findings with other sources of information on the TPPs, in particular, the collection of monitoring data undertaken at all the first and second wave TPPs by postal survey and telephone interviews in 1997/8. The case study analysis can be arranged into five groups: TPPs as organisations; tools and levers for achieving change; the scope and nature of benefits/outcomes for patients and populations; the position of TPPs within local commissioning systems; and management capability - costs and issues of sustainability. From this analysis the report draws the following conclusions about the implications for future primary care-based purchasing organisations. In operational terms, the characteristics associated with achievement were: the ability to hold and use budgets; the availability of adequate management resources; good relationships with external agencies, particularly the health authority; effective management systems; the presence of product champions both within the TPP but also in HAs and trusts; a strong dynamic executive management team; the inclusivity of stakeholders; the engendering of a collective responsibility and corporacy within the TPP; and a positive national and local context. In terms of service development, where there is vested local interest or enthusiasm, there tends to be more success than when the objectives are more strategic. A discussion of the implications of these findings for the future success of primary care organisations concludes the report.